Biomedical subjects

Xue Zhang

Publications and source records attributed to Xue Zhang.

62 records · Page 4Linked to original sources

PubMed2003

[Genomic variations in the locus for aminopeptidase N:a putative cellular receptor for SARS-CoV spike glycoprotein].

Aminopeptidase N has been identified as the cellular receptor for human coronavirus HCoV-229E and was a putative receptor for the spike glycoprotein encoded by the SARS-associated coronavirus (SARS-CoV). We report here identification of 9 single nucleotide polymorphisms (SNPs) in ANPEP, encoding human aminopeptidase N, in Chinese. All ANPEP exons and their flanking intronic sequences were amplified from unrelated normal individuals by polymerase chain reaction (PCR) and screened using denaturing high-performance liquid chromatography (DHPLC). Nine SNPs were revealed after direct sequencing of PCR amplified fragments which showed changes of DHPLC chromatogram. Four of these polymorphisms, T321M(962C > T), S651L(1952C > T), S752N(2255G > A) and G764R(2290G > A), were non-synonymous; the remaining exonic synonymous and intronic ones were T795T(2385C > T), IVS7 + 17G > A, IVS14-16A > G, IVS17 + 12C > G and IVS17 + 44C > T. Our data may be useful for studies to investigate the role of host genetic factors in SARS pathogenesis, especially for identifying SARS-susceptible and/or anti-SARS alleles.

Animals↗

PubMed2002

Identification and characterization of P15RS, a novel P15(INK4b) related gene on G1/S progression.

To screen genes involved in P15(INK4b) regulation during cell cycle, differential display method was applied to compare mRNAs from G(1) synchronized cells of MLIK6, which overexpressed P15(INK4b) gene, and its control MLC2. By using this approach, 15 cDNA fragments that were preferentially expressed in MLIK6 cells, but not in MLC2 cells, were screened out. A novel gene named P15RS was identified with further analysis. Combining the sequence from DD-PCR, homology analysis against EST database and RACE, a 4,404 bp complete cDNA sequence of P15RS was generated. Sequence analysis revealed that P15RS cDNA encoded a 312-amino-acid peptide containing a RAR domain that is involved in regulation of nuclear pre-mRNA, which suggests that P15RS may be a nuclear regulation protein. Genomic sequence analysis demonstrated that human P15RS gene was localized on chromosome 18q12 with seven exons and six introns. Expressing antisense P15RS in MLIK6 cells can up-regulate the expression of cyclinD1 and cyclinE. These data indicate that P15RS may act as a negative regulator in G(1) phase.

Amino Acid Sequence↗

PubMed2002

[Relationship between interleukin-1B and interleukin-1 receptor antagonist gene polymorphisms and susceptibility to gastric cancer].

OBJECTIVE: To investigate the polymorphisms of interleukin-1B (IL-1B) promotor region 31 C/T and interleukin-1 receptor antagonist (IL-1RN) gene and the relationship between the genotype of IL-1 and IL-1RN and susceptibility to gastric cancer in Chinese population. METHODS: Genomic DNA was extracted from the juxta-cancerous normal mucosal biopsies of 50 patients with gastric cancer taken by endoscopy and from the peripheral lymphocytes of 50 normal controls and then was subjected to PCR amplification. The PCR product was digested by restriction endonuclease Alu I. The product of digestion was subjected to 2% agarose gel electrophoresis and ethidium bromide staining. RESULTS: The IL-1B -31C allele was detected in 75% of normal controls and 53% of patients, while the IL-1B -31T allele was detected in 25% of normal controls and 47% of patients. The frequency of -31C/-31C was 56% (28/56) and 30% (15/50) in normal controls and patients respectively. The frequency of -31C/-31T was 38% (19/56) and 46% (23/50) in normal controls and patients respectively. The frequency of -31T/-31T was 6% (3/56) and 24% (12/50) in normal controls and patients respectively. IL-1B -31T carriers were at increased risk of gastric cancer with an odds ratio of 7.5 for -31T/-31T homozygotes (95% CI, 2.0 approximately 27.6) and of 2.3 for -31C/-31T (95% CI, 0.9 approximately 5.4) respectively. Only three of the five kinds of polymorphism of IL-1RN (1/1, 1/2 and 2/2) were found in this study. The frequency of 1/1 was 54% (27/50) and 24% (12/50) in normal controls and patients respectively. The frequency of 1/2 was 38% (19/50) and 50% (25/50) in normal controls and patients respectively. The frequency of 2/2 was 8% (4/50) and 26% (13/50) in normal controls and patients respectively. The IL-1RN * 1 allele was detected in 73% of normal controls and 49% of patients; while the IL-1RN * 2 allele was detected in 27% of normal controls and 51% of patients. IL-RN * 2 carriers were at increased risk of gastric cancer with an odds ratio of 7.31 for 2/2 homozygotes (95% CI 2.13 approximately 25.09) and of 2.96for 1/2 heterozygotes (95% CI 1.22 approximately 7.21), respectively. CONCLUSION: The polymorphism of promotor region -31C/T of IL-1B gene and the polymorphism of IL-1RN genes 1/2 and 2/2 are associated with the susceptibility of gastric cancer in Chinese. Carrying -31T allele increases the risk of gastric cancer. Polymorphism of IL-1RN and IL-1B gene may be used as indicators of susceptibility of gastric carcinogenesis.

Alleles↗

PubMed2002

[Construction and expression of mouse DOC-1R antisense gene vector].

BACKGROUND & OBJECTIVE: DOC-1R gene is a candidate tumor suppressor gene that when connected specifically with CDK2 can control the course of cell cycle by restraining the reciprocity of CDK2 and cyclin. The aim of this study was to construct the antisense DOC-1R plasmid and to investigate the effect of DOR-1R gene on the growth of normal cell. METHOD: The recombinant antisense plasmid was constructed after screening the expression of DOC-1R gene. Following transfection, the effect of DOC-1R on cell growth was determined by assessing the ability of cell replication and observing soft agar culture. RESULT: The growth speed of NIH3T3 transfected by mouse DOC-1R gene was of significant difference from that transfected by empty vector. The pcDNA3-DOC-1R+ vector significantly inhibited the cell replication, while the pcDNA3-DOC-1R- vector stimulated the cell replication. In soft agar culture, the colony formation capacity was decreased in the recombinant sense vector group. The clone formation rate was decreased and the size of the colony formed was smaller as well. In contrast, the colony forming ability was remarkably increased in the antisense vector group. The clone formation rate was increased significantly, compared to that in the sense group. CONCLUSION: Mouse DOC-1R gene can significantly inhibit cell growth and colony formation capacity. It will be helpful for the study on the mechanism of normal cell growth and replication as well as for research in tumor treatment and prevention.

3T3 Cells↗

PubMed2002

[Ectopic expression of cyclin G2 inhibits cell proliferation in HeLa cancer cell line].

BACKGROUND & OBJECTIVE: Cyclins are important proteins in cell cycle machinery, acting as positive regulators in cell proliferation. Cyclin G2 may exceptionally be a negative regulator since its expression could be induced by DNA damage and the VHL tumor suppressor protein. Furthermore, down-regulated cyclin G2 was detected in oral squamous cell carcinomas. The current study was aimed at clarifying the effects of cyclin G2 transgene expression on proliferation of cancer cells in vitro. METHODS: Cyclin G2 cDNA was synthesized by reverse transcription-polymerase chain reaction (RT-PCR) and inserted into the pIRESneo vector at BamH I and BstX I sites to generate the recombinant plasmid pIRES-G2. The pIRES-G2 and pIRESneo plasmids were then individually introduced into HeLa cancer cell line through lipofectamine mediated transfection. After two weeks' selection in culture medium containing G418, the number of colonies was counted and the transfectant cells were morphologically observed. RESULTS: The colony-forming efficiency of the cells transfected with pIRES-G2 construct was much lower compared with that with the control parental vector pIRESneo. The colony numbers were 76.7 +/- 24.8 and 18 +/- 10.4 in control and experimental groups, respectively, with a colony forming rate of 23.4% in the pIRES-G2 group. Furthermore, pIRES-G2 transfected cells showed a senescent morphology. CONCLUSION: Ectopic overexpression of cyclin G2 in cancer cell line HeLa could inhibit cell proliferation significantly.

Cell Division↗

PubMed2002

[Cloning and expression of the mouse Doc-1R gene].

BACKGROUND & OBJECTIVE: Doc-1R gene is a new gene which was cloned in 1999. Recent studies suggest that Doc-1R gene is a potential tumor suppressor gene. In order to study the function of the Doc-1R gene, The aim of this study was to obtain its genomic sequences and to analyze its expression in the tissues. METHOD: According to the cDNA sequences of Doc-1R gene, the gene-specific primers were designed and synthesized. The sequence of Doc-1R gene was cloned through nested PCR using the Genome Walker kit. The sequence and splice donor/acceptor site were analyzed. Using the reverse transcription polymerase chain reaction(RT-PCR), the expression of Doc-1R gene in thirteen tissues, including mouse liver, spleen, pancreas, kidney, lung, intestine, heart, brain, bone, muscle, bladder, ovary, spermary were determined. RESULTS: The mouse Doc-1R gene has been obtained by two times genomic walking. This gene spans 2,787 bp and contains four exons and three introns. All of the splice donor/acceptor site sequences were in accordance with the consensus "GT-AG" rule. RT-PCR experiments demonstrated Doc-1R gene was expressed in the 13 tissue samples. CONCLUSION: The authors have successfully cloned the mouse Doc-1R gene, which will be the foundation for further investigating the function of that gene. The expression pattern suggests that the Doc-1R gene is a housekeeping gene which is important to keep the function of tissues and organs.

Animals↗

PubMedDate not supplied

Three new bibenzyl derivatives from Dendrobium nobile.

Three new bibenzyl derivatives have been isolated from the stems of Dendrobium nobile Lindl. (Orchidaceae). Their structures were established as 4,5-dihydroxy-3,3',alpha-trimethoxybibenzyl (1), 4,4'-dihydroxy-3,3',5,alpha-tetramethoxybibenzyl (2) and 4-hydroxy-3,3',4',5,alpha-pentamethoxybibenzyl (3) on the basis of spectroscopic analysis.

Benzyl Compounds↗

PubMedDate not supplied

Tokay gecko photoreceptors achieve rod-like physiology with cone-like proteins.

The retinal photoreceptors of the nocturnal Tokay gecko (Gekko gekko) consist exclusively of rods by the criteria of morphology and key features of their light responses. Unlike cones, they display robust photoresponses and have relatively slow recovery times. Nonetheless, the major and minor visual pigments identified in gecko rods are of the cone type by sequence and spectroscopic behavior. In the ongoing search for the molecular bases for the physiological differences between cones and rods, we have characterized the molecular biology and biochemistry of the gecko rod phototransduction cascade. We have cloned cDNAs encoding all or part of major protein components of the phototransduction cascade by RT-PCR with degenerate oligonucleotides designed to amplify cone- or rod-like sequences. For all proteins examined we obtained only cone-like and never rod-like sequences. The proteins identified include transducin alpha (Galphat), phosphodiesterase (PDE6) catalytic and inhibitory subunits, cyclic nucleotide-gated channel (CNGalpha) and arrestin. We also cloned cDNA encoding gecko RGS9-1 (Regulator of G Protein Signaling 9, splice variant 1), which is expressed in both rods and cones of all species studied but is typically found at 10-fold higher concentrations in cones, and found that gecko rods contain slightly lower RGS9-1 levels than mammalian rods. Furthermore, we found that the levels of GTPase accelerating protein (GAP) activity and cyclic GMP (cGMP) phosphodiesterase activity were similar in gecko and mammalian rods. These results place substantial constraints on the critical changes needed to convert a cone into a rod in the course of evolution: The many features of phototransduction molecules conserved between those expressed in gecko rods and those expressed in cones cannot explain the physiological differences, whereas the higher levels of RGS9-1 and GAP activity in cones are likely among the essential requirements for the rapid photoresponses of cones.

Animals↗